Luckily I have plenty more soil available and thanks to my daughter bringing me home about 200 Wallflower plug plants I can fill it up for winter to stop the cats using it as a toilet.
I'm thinking we have a slight land drainage problem
When we first moved here 3 acres or so was completely plastered in awful gorse bush. We wasted way too much time and money trying to clear it without researching the correct way to go about it, this resulted in us simply regenerating new growth. We finally decided to pull all the gorse out with a digger, scrape the whole land with a digger and then literally go round pulling up all the little bits of roots that we could find. We now have land that can be mowed but we still haven't resolved the gorse problem - it really is a tenacious plant that isn't even destroyed by fire - we tried!
We can live with it though because the mowing will prevent it gaining any height and we thought it eould eventually stunt the overall health of whatever was left.
No such luck!
See all that dark green stuff? That's gorse and it's decided that if it can't grow up it will make a lovely prickly carpet instead.